Sergio Martinez (shown) celebrates after defeating Sergiy Dzinziruk in their WBC middleweight title fight in March '11. (AP photo)

“At 37, he’s not a youngster chronologically, but he hasn’t taken a lot of punishment as a fighter,” promoter Lou DiBella said.

He didn’t look like the Martinez many have come to expect, however, when he knocked out Barker in the 11th round of their title fight in Atlantic City, N.J., on Oct. 1.

Barker was far more competitive than anyone other than his family might have imagined and Martinez seemed to lack zip.

The answer, Martinez said, was not age. It was injury. He hurt his left elbow in training, but in the second round, he dislocated it.

“I threw a punch the wrong way and it really began to hurt me,” Martinez said.

Given that Martinez is left-handed, losing the use of his dominant hand would qualify as a decent explanation for a lackluster performance. Andre the Giant excelled in handicap matches during his pro wrestling days, but there haven’t been too many boxers who have done it.

Macklin has promised that Martinez “is going to feel every one of those 37 years,” but Martinez is hardly concerned. He’s No. 3 in the Yahoo! Sports rankings largely because he’s won when he’s expected to win.

He’s pleaded for a fight against one of the big two, No. 1 Floyd Mayweather Jr. or No. 2 Manny Pacquiao, and in January, Mayweather opened the door for a Martinez fight ever so slightly.

Mayweather said he’d consider a fight against Martinez if Martinez could successfully make 150, which is three pounds above the welterweight limit where Mayweather regularly competes and 10 pounds below the middleweight division limit, where Martinez is the kingpin.

“If Sergio Martinez can make 150, let’s make the fight happen,â Mayweather told Yahoo! Sports on Jan. 18. “Like I said, there are no excuses. I’m a little different than other guys. He’s got a very, very impressive style.”

Martinez faces a conundrum of sorts on Saturday, though. Mayweather has subsequently signed to fight Miguel Cotto on May 5 for the World Boxing Association super welterweight title, but have no doubt that Mayweather will keep an eye on how Martinez looks as an option for a bout later in the year.

The problem facing Martinez is that he must win, but if he looks too good in doing so, Mayweather’s team might conclude he’s too big and too much of a risk. If he loses, there is no chance for one of those career-defining fights he dreams about. He’d maximize his opportunity to get Mayweather into the ring with a winning performance in which he looks vulnerable.

“I’m not worried about Mayweather right now,” Martinez said. “This fight [with Macklin] is the most important thing in the world to me right now. Nothing else matters.”

There is no opponent at middleweight who would define Martinez’s legacy and bring him the big-money payday he craves than Mayweather. Julio Cesar Chavez Jr., who holds one of the belts that was stripped from Martinez in the typically bizarre sanctioning body politics that all too frequently occur in boxing, has a big name and a passionate fan base. The public, though, doesn’t see Chavez as a legitimate challenge for Martinez.

There is no one at middleweight who fills the bill. And while Martinez could look up at super middleweight, the truth is, he’s a small middleweight who should be fighting at super welterweight.

“Sergio’s eating steak and potatoes and he’s not having trouble with his weight,” DiBella said. “He’s just not that big of a guy at middleweight. Guys like [Lucian] Bute and Andre Ward at super middleweight, they walk around 25, 30 pounds heavier than Sergio. There’s a profound size difference there.

“He really should be at 154, but he’s campaigning at 160 because no one would fight him at [super welterweight].”

Martinez isn’t eager to talk about much other than Macklin. He knows that fighting an Irishman in New York on St. Patrick’s Day isn’t going to be easy. DiBella estimates that upwards of 70 percent of the crowd will be Irish.

And Martinez believes that Macklin will perform better than he ever has, knowing everything rides on this fight.

That’s just the way he wants it, though.

“I don’t know why I get criticized, because I won all of the belts and I have done a great job in all of my [defenses],” he said. “I am healthy and I am in great shape and I want to remind everyone what I can do when I’m that way.”

If he looks good – but not too good – he may finally put himself into position to land that career-defining bout he’s longed dreamed about getting.